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김동준,정종문,김정현,황하청,정재윤,조윤희,임현교,구제환,최은하,조광섭,Jin, D.J.,Jeong, J.M.,Kim, J.H.,Hwang, H.C.,Chung, J.Y.,Cho, Y.H.,Lim, H.K.,Koo, J.H.,Choi, E.H.,Cho, G.S. 한국진공학회 2010 Applied Science and Convergence Technology Vol.19 No.1
관경이 수 mm인 세관 램프 내부에서 플라즈마의 확산을 조사하기 위하여 이극성(ambipolar) 확산방정식을 해하였다. 반경 방향의 확산에 의한 유리관 벽에서의 플라즈마 소멸 특성시간은 $\tau_r\;=\;(r_0/2.4)^2/D_a$로 주어진다. 반경 $r_0{\sim}1\;mm$이고 이극성 확산계수 $D_a{\sim}0.01\;m^2/s$ 이면, $\tau_r{\sim}17\;{\mu}s$이다. 이는 램프의 교류전원 구동에서 플라즈마를 유지하기 위한 구동 최소 주파수 ~30 kHz에 해당한다. 고전압이 인가되는 전극부에 발생한 고밀도의 플라즈마가 양광주로 확산되는 특성시간은 $\tau_z{\sim}0.1\;s$이다. 고밀도 플라즈마 경계에서의 시간에 대한 확산속도는 $t{\sim}10^{-6}\;s$일 때 $u_D{\sim}10^2\;m/s$이고, $t{\sim}10^{-3}\;s$이면 그 속도는 $u_D{\sim}1\;m/s$로 느려진다. 따라서 램프 길이 ~1 m에 대하여 전극부에서 생성된 고밀도 플라즈마가 양광주 전체로 확산되는 시간은 수 초가 걸린다. The ambipolar diffusion equation has been solved in a fine-tube lamp of a few mm in diameter. In the diffusion of radial direction, the plasma diffuses and vanishes away at the glass wall by recombination with the characteristic time of plasma loss is given by $\tau_r\;=\;(r_0/2.4)^2/D_a$. With the radius $r_0{\sim}1\;mm$ and the ambipolar diffusion coefficient $D_a{\sim}0.01\;m^2/s$, the vanishing time is calculated $\tau_r{\sim}10\;{\mu}s$ which corresponds to the least value of frequency 30 kHz for the sustaining the plasma in the operation of high voltage AC-power. In the diffusion of longitudinal z-direction, a high density plasma generated at the area of a high voltage electrode, diffuses into the positive column with the characteristic time $\tau_z{\sim}0.1\;s$. The plasma diffusion velocity at the boundary of high density plasma is $u_D{\sim}10^2\;m/s$ at the time $t{\sim}10^{-6}$ s and the diffusion velocity becomes slow as $u_D{\sim}1\;m/s$ at $t{\sim}10^{-3}\;s$. Therefore, for the long lamp of 1 m, it takes about several seconds for the high density plasma at the area of electrode to diffuse through the whole positive column space.
김동준(D.J. Kim),이종주(J.J. Lee),문영환(Y.H. Moon) 대한전기학회 2010 대한전기학회 학술대회 논문집 Vol.2010 No.11
This paper describes the dynamic modeling of Doubly-Fed Asychronous generator (DFAG) including both rotor and PLL dynamics for transient stability study in power systems. The suggested DFAG machine model uses the stator field orientation reference frame and Per Unit generator parameters. This suggested DFAG model is verified by running both the steady state conditions and rotor current step dynamic test using 6-machine and 23-bus system.
용융 열처리한 PMMA/Alumina 복합체의 기계 특성
김동준 ( D. J. Kim ),류수착 ( S. C. Ryu ) 한국열처리공학회 2018 熱處理工學會誌 Vol.31 No.3
The PMMA composited material mixed with alumina studied to find the optimal condition, the ade-quate ratio of mixing, for the associated mechanical properties such as anti-corrosive, weatherproof perfor-mance. The 80% of hardness and 52% of scratch coefficient improved according to increasing ratio of alumina, which is mostly 3 times higher than that of pure PMMA, on other hand 16% of tensile strength and 35% of flex-ural strength has lost while alumina was adding in. The most proper ratio, having the best availability in substan-tial production, of composite between pure PMMA and alumina is determined as 93 wt. % vs 7 wt. %. Results of related five properties had estimated by using of a pentagram. (Received April 25, 2018; Revised May 3, 2018; Accepted May 10, 2018)
증례 : 아메바성대장염에 유발된 다발성 관절염의 1 치험례
김동준 ( D. J. Kim ),조승환 ( S. H. Cho ),김홍수 ( H. S. Kim ),서주영 ( C. Y. Suh ) 대한내과학회 1968 대한내과학회지 Vol.11 No.4
1. A case of polyarthritis secondary to amebic colitis is reported, and this is considered to be a first case in Korea. 2. The diagnosis of amebic colitis was established by the isolation of the ameba from the stool and the subsequent rapid response of the